The present invention relates to an alarm information transmission system for coin telephone and, more particularly, to an alarm information transmission system with a self diagnosis function.
Coin telephone systems with a self diagnosis function have been known. It is also known to transmit alarm information from such a conventional coin telephone to a control side in accordance with diagnosis result.
A self diagnosis function of a coin telephone (to be referred to as a telephone set hereinafter) is disclosed in detail in European Patent Publication No. 0012102 (July 18, 1984). An alarm information transmission system of the telephone set is disclosed in Japanese Patent Disclosure No. 58-156259. These prior art systems are operated to perform self diagnosis or transmit alarm information upon formation of a DC loop upon off-hook operation by a user.
Since coin telephone sets at rural areas are not often used, failure detection of the sets is delayed in such areas. Furthermore, when a consignee judges that the telephone set is broken and attaches a note "Out of Order" to the telephone set, the telephone set will not be hooked off. Unless a failure message is received by maintenance personnel through another telephone line, the maintenance control center cannot know the failure. The broken telephone set may then be left unrepaired, and the maintenance control center cannot provide best service to the users.